1. Technical Field
The present invention relates to a projection display device with a position detection function, capable of projecting an image and at the same time optically detecting a position of an object matter located on the side from which the image is projected.
2. Related Art
In recent years, display devices with a position detection function each having a touch panel disposed on the front of an image generation device such as a liquid crystal device are used for electronic devices such as cellular phones, car navigation systems, personal computers, ticket-vending machines, or banking terminals, and in such display devices with a position detection function, information is input with reference to an image displayed on the image generation device. Such touch panels are each configured as a position detection device for detecting a position of an object matter in a detection area (see, e.g., FIG. 6 of JP-A-2001-142643 (Document 1)).
The position detection device described in the Document 1 is of an optical type, and has a configuration of setting a detection area on the side of the display surface for displaying an image in the direct view display device, and having a plurality of light emitting diodes and a plurality of photo transistors disposed on both sides across the detection area. In such a position detection device, if the object matter enters inside the detection area, the light is blocked by the object matter, and therefore, by identifying the phototransistors the light to which is blocked, the position of the object matter can be detected.
Further, there is proposed a position detection device having a translucent plate disposed on the side of input operations with respect to a direct view display panel such as a liquid crystal panel, and a light source and a light receiving element disposed on the side opposite to the side of input operations with respect to the translucent plate (see, e.g., U.S. Pat. No. 6,927,384 (Document 2)).
In such a position detection device described in the Document 2, the position detection light emitted from the light source is emitted toward the side of input operations via the translucent plate, and the position detection light reflected by the object matter is received by the light receiving element.